Do You Need to Train to Failure to Grow Muscle?

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Success isn’t always about greatness. It’s about consistency. Consistent hard work gains success. Greatness will come.
––Dwayne “The Rock” Johnson

In the lifting community, some people believe you must go to failure on every single set because, “no pain, no gain, bro!”
 
Other people claim you must avoid failure because, “injury and fatigue, bro!”
 
But which one is the best approach to optimal muscle growth? Is there a single best approach?
 
This article will tackle these questions and cover the following points:
 

• What is muscular failure?
• Is it necessary to grow muscle?
• When would you want to train to failure?

What is muscular failure?
 
A journal article from 2016 defined muscular failure as “the inability to move a specific load beyond a critical joint angle or (…) incapacity to complete a repetition in a full range of motion due to fatigue.”
 
For example, when you reach muscular failure on the bench press, you can’t push the bar off your chest, so you squirm in a rather undignified manner and wave your hand at the person next to you to get help. I might or might not be speaking from experience.
 
You may have also heard the term technical failure, which occurs when you can’t perform another repetition with correct technique.
 
For instance, on an ass-to-grass squat, you would reach technical failure when you start doing quarter squats.
 
Throughout this article, I will be referring primarily to muscular failure.
 
Is muscular failure necessary to grow muscle?
 
Before we can get to the answer, we need to start from the following question: How does muscle growth happen?
 
First off, muscle growth is a complex process, which we don’t fully understand yet.
 
In humans, muscle growth seems to occur primarily through a physiological process called hypertrophy, which is an increase in the size of the muscle cells (also referred to as muscle fibres).
 
It can also take place through hyperplasia, which is an increase in the number of muscle fibres. This appears to be more common in animals than humans. 
 
To trigger a muscle fibre to grow bigger, we need to apply an appropriate amount of tension to it. When we lift a load, the muscle fibres involved in the movement will experience the tension created by the load.
 
Does that mean you don’t need to reach failure, because, as soon as you start curling that EZ bar, the muscle fibres in your biceps will get all the sweet tension they need? Not exactly.
 
The thing is, we don’t immediately start using 100% of the fibres in our muscles the moment we begin a set. And, the more muscle fibres contribute to a set, the higher the number of fibres that receive a stimulus to grow. If more fibres within the same muscle grow, that muscle will experience more overall development than if a smaller number of its fibres undergo hypertrophy.
 
Furthermore, fast-twitch fibres seem to be more likely to hypertrophy than slow-twitch ones. All the more reason to want to recruit them!
 
So how do we recruit our muscle fibres?
 
Each fibre is connected to a neuron, and each neuron in turn is linked to a number of fibres. Neurons give the fibres the order to activate and contribute to a movement. A neuron and all of the fibres it “supervises” – or innervates, in technical terms – is called a motor unit.
 
These motor units are then fired according to Henneman’s size principle, which states that higher-threshold motor units are activated last.
 
These “higher-threshold motor units” are made up of fibres known as fast-twitch fibres, which can produce a lot of force, but also fatigue fast, as opposed to slow-twitch fibres, which produce less force, but can keep going for longer.
 
At the beginning of a set, slow-twitch fibres are the first to be recruited. The closer we get to failure, the harder the movement becomes and thus the more force we need in order to complete it. That’s when we start recruiting our fast-twitch fibres.
 
This explains why training close to failure is a good idea: if you don’t do that, you won’t recruit many, if any, fast-twitch fibres, which appear to be the best responders to a growth stimulus.
 
In that case, is failure training superior for hypertrophy?
 
The answer to this is not so clear-cut.
 
Indeed, going to failure is a fool-proof way to recruit all of the fibres within a muscle. However, this also produces the highest amount of fatigue, which might compromise your training performance within the same session and over a longer period of time.
 
Furthermore, it is possible recruit higher-threshold motor units without hitting failure on every single set. Indeed, it looks like staying within four to five reps from failure may be more than enough to make gains that are similar in magnitude to those you would make by going to failure all the time.
 
Therefore, you could go to failure on every set to make sure you are always recruiting all of your fibres. However, the evidence on whether this approach is superior to training just shy of failure is limited and mixed at the moment.
 
On the other hand, we can be pretty sure that training close to failure will help us make good gains, and it can allow us to manage fatigue a little bit better than failure training. The only downside is that it can be easy to think you are training “hard enough”, when in fact you are way too far from failure to see any changes in your muscular development.
 
A tool I have found most helpful to reach the appropriate proximity to failure whilst improving fatigue regulation in my own and my clients’ training is the RPE or RIR scale.
 
When could you benefit from training to failure?
 
Now you know that you don’t need to train to failure to optimise muscle growth, but you still need to train hard enough to make it happen.
 
Nevertheless, I’m not suggesting you avoid failure training altogether. In fact, it can prove useful in a variety of scenarios, such as the following:

• Instead of aiming for the same RPE target every week, you could start from three or four reps away from failure and increase intensity of effort every week until you hit failure in the final week of your training block, then you deload and repeat. This is what I have been doing in my own training for over a year as of October 2020.
• If you haven’t taken a set to failure in a long time, and you aren’t so sure you are training hard enough, you can go to failure on the last set of each exercise in your session to see where you are at (using a “last set, best set” approach).
• If you have never experienced failure, then it is unlikely you can use the RPE or RIR scale because you simply don’t know what “failure” means. Therefore, going to failure on various exercises with which it is safe to do so can teach you what true failure feels like in each muscle in your body.
• If you know you tend to “chicken out” of a set unless you train to failure, then maybe this is the best training approach for you. Training too far from failure is not superior to hitting failure, so, if you know you can’t reach the appropriate proximity to failure using the RPE or RIR scale, then perhaps failure training will give you the most bang for your buck.
• Some people find that overcomplicating their training puts them off of it. If that’s the case, and you think that RPE and RIR are way too convoluted methods to gauge progress, failure training might be the best way for you to adhere to your training program. And, in the end, you can’t make gains if you don’t train, so go for what helps you stay consistent.

 
Final Thoughts
 
There is a time and place for failure training, just like there is a time and place for leaving reps “in the tank”.
 
The key to optimal gains is the understanding that neither is a magic ticket to the Valley of Muscle.
 
Among approaches that science has not yet deemed completely counterproductive, the best one is ultimately the one enjoy the most and can apply it with the utmost consistence.
 
Your Turn:
 
How do you use failure in your training? Let me know in a comment.